Your third book, David Courtwright’s Violent Land, explores why America is more violent than other democracies, and why certain Americans are more violent than others.

Why is America so much more violent than other democracies? Why is the American South and Southwest so much more violent than the rest of the country? Why are African-Americans more violent than Americans of European descent? Courtwright takes on these puzzles in a rich narrative which weaves American history with evolutionary psychology and neurobiology.

He argues that large parts of America were settled by young men living in anarchy. These are the ingredients for violent competition for dominance, which puts a premium on a reputation of toughness and resolve. He notes that young men’s competition for dominance was necessary for access to mating opportunities with women, in settings in which either the women are scarce and have to be fought over, or there is de facto polygamy, so a dominant man can have access to many females, leaving the not-so-dominant men mateless.

The stereotype of the Wild West from the old cowboy movies is historically accurate. The American West – the gold rush towns, the mining camps, the itinerant workers’ camps in expanding America – saw horrendous rates of male-on-male killing. With murder statistics there was, as he puts it, “an abundance of other evidence that Gold Rush California was a brutal and unforgiving place. Camp Names were mimetic: Gouge Eye, Murderers’ Bar, Cut-Throat Gulch, Graveyard Flat. There was a Hangtown, a Helltown, a Whiskeytown, and a Gomorrrah, though, interestingly, no Sodom.”

Courtwright also argues that the American West was eventually civilised by women. Once women started to seek their fortunes in the marriage market by moving west, they had the bargaining power to force the men into a civilised lifestyle more suited to their interests. The women spearheaded temperance movements to reduce drunken brawling, and joined forces with the church to force men into church and family life. They also worked to shut down the saloons and brothels, to steer the men away from their lives of boozing, whoring, brawling and gambling.

I suspect that this combination of history and sociobiology solves a puzzle that has long baffled liberal America and Europe – why red-state America fetishises religion, sexual propriety and “family values”.

Much more so than in the UK, for example.

Very much more so, and far more than in the northern and coastal United States – the divide we call “the culture war”. Based on Courtwright’s history, I suspect that the split arose from a history in which the American West, Southwest and South were largely civilised by women and the church, whereas the Northeast – like Europe – was civilised by government, commerce and the court system.